Update Fold + Env to allow for filters for instance status

[oswynb]

Add a 'Filters' to the Env to supply ceilometer-common with a predicate to filter Instance metrics based on status.

[tranma]

I'm not sure how this is supposed to work. Say you have events:

                                                 query end somewhere here
                                                 v
InstanceActive | InstanceSuspended | InstanceResize 
       ^ 
       query start somewhere here

and InstanceSuspended is not "billable", so you just ignore the time delta between start and InstanceSuspended, but you don't change the accumulator, so you end up adding the delta between start and InstanceResize -- that wouldn't change the result at all, would it?

Can you put an example here so we can see?

[tranma]

Ah, I see. It's a bit convoluted, I can't think of a cleaner way on the top of my head. Regardless, could you add some quickcheck tests, for both instance flavors and non-flavor resources?

[tranma]

if we have quickcheck tests, we can formulate exactly what we're expecting here.

[oswynb]

Shall do

[tranma]

tests/SampleData has all the Arbitrary & friends instances

[olorin]

I think this needs a minor bump?

[tranma]

can you put a short comment describing this property -- something to the effect of "filtered results must be subset of ... and all filtered values are less than corresponding values in full results"

then please merge.

[tranma]

sign-off.

[olorin]

This use of "describe" is odd - normally, describe is used to name the thing which is described by the tests, not assert that the thing is sane.

[tranma]

describe "filtering instance statuses" $
prop "is sane" ....

[olorin]

Yep.